A new enhancement method is proposed based on the characteristics of fundus images in this paper. Firstly, top-hat transform is utilized to weaken the background. Secondly, contrast limited adaptive histogram equalization (CLAHE) is performed to improve the uneven illumination. Finally, two-dimensional matched filters are designed to further enhance the contrast between blood vessels and background. The algorithm was tested in DIARETDB0 databases and showed good applicability for both normal and pathological fundus images. A new no-reference image quality assessment method was used to evaluate the enhancement methods objectively. The results demonstrated that the proposed method could effectively weaken the background, increase contrast, enhance details in the fundus images and improve the image quality greatly.
Considering the survival rate of small animals and the continuity of the experiments, high-dose X-ray shooting process is not suitable for the small animals in computed tomography (CT) experiments. But the low-dose process results with images might be polluted by noises which are not conducive for the experiments. In order to solve this problem, we in this paper introduce a global dictionary learning based denoising method to apply the promotion of the low dose CT image. We at first adopted the K-means singular value decomposition (K-SVD) algorithm to train a global dictionary based on the high dose CT image. Then, the noise image could be decomposed into sparse component which was free from noise through the orthogonal matching pursuit (OMP) algorithm. Finally, the noise-free image could be achieved by reconstructing the image only with its sparse components. The experiments results showed that the method we proposed here could decrease the noise efficiently and remain the details, and it would help promote the low dose image quality and increase the survival rate of the small animals.
ObjectiveTo summary the safety and efficiency of the minimally invasive direct cardiac surgery (MIDCS) approach in elderly patients with heart disease. MethodsWe retrospectively analyzed the clinical data of 60 patients underwent MIDCS in Beijng Anzhen Hospital between April 2010 and January 2013. There were 34 males and 26 females with mean age of 66.4±4.8 years and mean weight of 66.1±10.6 kg. ResultsMean cardiopulmonary bypass time and aortic cross-clamp time was 141.2±57.2 minutes and 99.8±37.6 minutes respectively. A total of 37 patients (90.2%) recovered to beat automatically after heart ceased operation. Median mechanical ventilation time was 17.1±9.1 hours. Mean intensive care unit stay was 22.1±12.2 hours. Mean post operative hospital stay was 7.0±2.5 days. Mean incision length was 5.3±0.9 cm. Mean pericardial draining volume was 466.6±412.1 ml in the first day after operation. No transfusion occurred in 27 (45.0%) patients. Early postoperative mortality was 3.3% (2/60). There were 2 patients of reexplorations for bleeding, 1 patient of the twice tracheal intubation, 1 patient of cardiac arrest after operation, 2 patients of poor healing of skin incision, and 1 patient of injury of right phrenic nerve. When leaving hospital, 47 patients were in heart functional class Ⅰ, 8 patients in class Ⅱ, and 3 patients in class Ⅲ. ConclusionMIDCS is associated with good operative effect in the near future with superior safety and broad application range in elderly patients with heart disease.